Fix for invalid 'extends/implements/with SomeEnum'.

pkg/analyzer/lib/src/summary/link.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * This library is capable of producing linked summaries from unlinked
  * ones (or prelinked ones).  It functions by building a miniature
  * element model to represent the contents of the summaries, and then
  * scanning the element model to gather linked information and adding
  * it to the summary data structures.
@@ skipping 521 matching lines @@
   }
 
   @override
   String get identifier => name;
 
   @override
   List<InterfaceType> get interfaces => _interfaces ??=
       _unlinkedClass.interfaces.map(_computeInterfaceType).toList();
 
   @override
+  bool get isEnum => false;
+
+  @override
   bool get isMixinApplication => _unlinkedClass.isMixinApplication;
 
   @override
   bool get isObject => _unlinkedClass.hasNoSupertype;
 
   @override
   LibraryElementForLink get library => enclosingElement.library;
 
   @override
   List<MethodElementForLink> get methods {
@@ skipping 109 matching lines @@
 
   @override
   String toString() => '$enclosingElement.$name';
 
   /**
    * Convert [typeRef] into an [InterfaceType].
    */
   InterfaceType _computeInterfaceType(EntityRef typeRef) {
     if (typeRef != null) {
       DartType type = enclosingElement.resolveTypeRef(typeRef, this);
-      if (type is InterfaceType) {
+      if (type is InterfaceType && !type.element.isEnum) {

[Brian Wilkerson, 2017/01/28 17:18:39]

Then it could be used here.

         return type;
       }
       // In the event that the `typeRef` isn't an interface type (which may
       // happen in the event of erroneous code) just fall through and pretend
       // the supertype is `Object`.
     }
     return enclosingElement.enclosingElement._linker.typeProvider.objectType;
   }
 }
 
@@ skipping 43 matching lines @@
         _fields.add(new FieldElementForLink_EnumField(value, this));
       }
     }
     return _fields;
   }
 
   @override
   List<InterfaceType> get interfaces => const [];
 
   @override
+  bool get isEnum => true;
+
+  @override
   bool get isObject => false;
 
   @override
   List<MethodElementForLink> get methods => const [];
 
   @override
   List<InterfaceType> get mixins => const [];
 
   @override
   String get name => _unlinkedEnum.name;
@@ skipping 4238 matching lines @@
    * there are no type parameters in scope.
    */
   TypeParameterizedElementMixin get _typeParameterContext;
 
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
   @override
   String toString() => '$enclosingElement.$name';
 }